Project Summary Recent data suggest that diabetes is common in patients hospitalized with severe COVID-19 illness, and hyperglycemia during hospitalization has been associated with poor outcomes in this patient population. As with other infections, ensuring good glycemic control will be important for optimizing the care of patients admitted with COVID-19; however, frequent glucose monitoring is time consuming, requires donning of personal protective equipment (PPE), and exposes healthcare workers to infection. The Dexcom G6 Continuous Glucose Monitoring (CGM) System provides real-time glucose data every 5 minutes and is approved for use in patients ages 2 and older in the outpatient setting. The FDA has recognized the potential value of using CGM to allow hospital staff to remotely monitor glucose in inpatients with COVID-19, releasing a statement that they will not object if CGM companies provide devices and technical support to hospitals who want to implement CGM for glucose monitoring to support COVID-19 healthcare efforts. Using the Dexcom G6 to monitor patients? glucose levels remotely in real-time could significantly improve diabetes management by alerting providers to high or low glucose values, reducing the burden of frequent in-person fingerstick glucose checks, limiting viral exposure of healthcare providers, and conserving PPE. However, given the lack of data confirming the accuracy of this device in the hospital setting, particularly in critically ill patients with COVID-19, the introduction of this technology into clinical use in the hospital and ICU setting requires a systematic approach to evaluate accuracy and safety prior to widespread use. We have developed a plan for introducing the Dexcom G6 into clinical use at Massachusetts General Hospital (MGH), using iterative quality assurance processes and comprehensive data collection to ensure safety and efficacy in this population. This will provide timely, real-life data to guide other health care organizations in the use of this technology during the COVID-19 crisis. In this proposal, we will pursue the following three aims: (1) we will establish the accuracy of the G6 CGM in patients admitted in an ICU and on a medical floor, identifying factors that may impact CGM accuracy and instituting a calibration protocol to improve accuracy if needed; (2) we will investigate the feasibility of non-adjunctive use of the Dexcom G6 in critically ill and non-critically ill patients admitted with COVID-19; and (3) we will evaluate the safety and efficacy of the Dexcom G6 in hospitalized patients with COVID-19 in a nested case-control study of patients with diabetes admitted to MGH. The data collected in this proposal will provide critical information guiding Aim 3 of the parent grant, which proposes to study an artificial pancreas device, the bionic pancreas (BP), in patients with cystic fibrosis related diabetes. Similar to those with COVID-19, patients with CF are often hospitalized with respiratory compromise, hypoxia, and hemodynamic instability. The BP utilizes the Dexcom G6 for glucose monitoring, so acquiring data on the accuracy and performance of the Dexcom G6 in hospitalized COVID-19 patients would be very valuable for informing this aim of the R01.